1. Field of the Invention
The invention relates to a routing display for a navigation system in a road vehicle in the form of an electro-optical display that is drivable by a routing computer, and which is able to use symbols to display a direction of current travel and a direction which is to be taken after a turn-off point relative to one another. The invention also relates to a method for showing routing information.
2. Description of the Related Art
In navigation systems, routing is carried out by outputting routing information via an audio or visual output unit. It has been found to be particularly useful for the visual display of routing information to show arrows which indicate to the driver the direction in which he needs to turn off at the next turn-off point. It is of particular importance that the driver receive an indication of whether this turn-off maneuver is immediately imminent or whether it is only needed after a relatively long distance in addition to the pure turn-off information. For this purpose, the distance to the turn-off point can be indicated directly, for example. However, a problem with this indication is that it can be registered by the driver only with difficulty during the journey. References EP 0 542 331 A1 and DE 44 12 859 C2 disclose routing displays in which a distance indication is integrated visually into a routing symbol. In accordance with the disclosure of EP 0 542 331 A1, the next turn-off point such as, for example, a roundabout is shown in detail. Furthermore, the distance already traveled and the distance which is still to be traveled are displayed by different colors. If this representation is to scale, then the driver is able to estimate the approximate distance to the turn-off point. However, this mode of representation is suitable only when the vehicle is already in the direct vicinity of the turn-off point, since only then is it possible to obtain an indication of the distance to the turn-off point from the geometric extent of the turn-off point and the position of the vehicle. Furthermore, reference DE 44 12 859 C1 discloses a routing display in which a bar graph forms the shaft of a direction arrow, with the active bar which is furthest away from the arrow tip representing the current distance to the turn-off point, and moving toward the arrow tip as this distance decreases. In addition, the book by Stefan Schlott: Fahrzeugnavigation: Routenplanung, Positionsbestimmung, Zielfxc3xchrung [Vehicle Navigation: Route Planning, Position Finding, Routing], Verlag Moderne Industrie, 1997 discloses, in FIG. 18, the practice of outputting different routing instructions on the basis of the distance of the vehicle from the turn-off point. In this context, a distinction is drawn between acknowledgement of a direction taken, an advance instruction and an instruction. The advance instruction is composed of two separate arrows, but permits no indication of the distance to the turn-off point.
The object of the present invention is to specify a routing display for a navigation system which is used to give the driver a visual impression of the distance to the next turn-off point. In particular, this routing display is intended to be able to be used for advanced warning instructions. Another object of the present invention is to specify a corresponding method for showing routing information.
The object is met by a routing system by in which the symbols for the direction of current travel and the direction which is to be taken after a turn-off point are changed in terms of their sizes relative to one another on the basis of the distance to the turn-off point. In one embodiment, the relative size of the symbol marking the direction which is to be taken after the turn-off point increases as the turn-off point is approached. As a result of this, the display unit gives the driver the visual impression that the turn-off point is getting closer. This visual impression may be achieved by changing the size of only one of the two symbols being changed while the size of the other symbol remains unchanged as stated above. Alternatively, the size of both symbols may be changed. In this context, the size of one or both symbols is preferably changed in two dimensions, i.e. both the length and the width of the symbol are changed. This gives a particularly clear representation of the change.
In one embodiment of the present invention, the symbols may additionally be changed in terms of their relative distance from one another. This allows the effect of approaching the junction to be clearly enhanced when looking at the routing display.
In a preferred embodiment, at least one of the symbols is an arrow display, with the arrow display being particularly preferred for the direction which is to be taken after the turn-off point. This gives a clear indication of the direction which is to be taken. In addition, the two symbols do not need to be completely physically separate from one another, but instead may also be close together or even connected to one another. Particularly in the latter case, a colored distinction between the symbols is preferred, since it is then possible to quickly separate the symbol for the direction of current travel from that for the direction which is to be taken after the turn-off point.
The object of the present invention is also met by a method for showing routing information from a navigation system for road vehicles on an electro-optical display which is driven by a routing computer and on which a direction of current travel and a direction which is to be taken after a turn-off point are displayed relative to one another using symbols. According to the inventive method, the distance to the turn-off point is determined and the symbols for the direction of current travel and the direction which is to be taken after the turn-off point are changed in terms of their sizes relative to one another on the basis of the distance to the turn-off point.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.